computing & information sciences kansas state university wednesday, 10 dec 2008cis 530 / 730:...

Computing & Information SciencesKansas State University

Wednesday, 10 Dec 2008CIS 530 / 730: Artificial Intelligence

Lecture 41 of 42

Wednesday, 10 December 2008

William H. Hsu

Department of Computing and Information Sciences, KSU

KSOL course page: http://snipurl.com/v9v3

Course web site: http://www.kddresearch.org/Courses/Fall-2008/CIS730

Instructor home page: http://www.cis.ksu.edu/~bhsu

Reading for Next Class:

Chapters 1-14, 22 – 23, 26, Russell & Norvig 2nd edition

Philosophy of MindDiscussion: Final Exam Review



PHILOSOPHY OF MINDPHILOSOPHY OF MIND

© 2006 Hilary Greaveshttp://www.rci.rutgers.edu/~hgreaves/teaching/phil103/lectures.htm



The Two Central Problems in the Philosophy of Mind

The Two Central Problems in the Philosophy of Mind

The Problem of Other Minds How can I know that other minds exist?

Vs.

ThoughtsFeelings

Sensory experiencesetc.



The Problem of Other Minds (cont’d)The Problem of Other Minds (cont’d)

How can I know what is going on in other minds?

AfraidLooking

forward to next

summer’s holiday

Vs.



The Mind – Body ProblemThe Mind – Body Problem

How are minds and their contents related to the physical, chemical & biological world?

MIND

MIND



Two (apparently unique) aspects of mental phenomena

Two (apparently unique) aspects of mental phenomena

Consciousness Your mind is conscious. But as far as we know, ordinary bits of physical matter are not

conscious. “What is consciousness?”

You know!

CONSCIOUS-NESS

CONSCIOUS-NESS



Intentionality (or aboutness)Intentionality (or aboutness)

Mental states can be about other things in the world. Your thought that Bush is a jerk is about George Bush.

Bush is a jerk

aboutness



Intentionality/aboutnessIntentionality/aboutness

Ordinary physical objects aren’t about anything. The desk is not about the chair.

aboutness




(A painting can be about something...

aboutness




... But that’s only because it was painted by someone who was thinking about the thing he was painting.)

aboutness



Terminological noteTerminological note

‘Intentionality’ has no special connection to intentions. Bush’s knowledge that Saddam Hussein is alive is about Saddam. Tom’s fear of the dentist is about dentists. My desire that Australia will be fun is about Australia. Your intention to eat dinner this evening is about your dinner.

Mental states that have ‘aboutness’ (=‘intentionality’)




The challenge: an adequate explanation of what minds are should explain how mental goings-on can be about things, since ordinary physical goings-on do not have this feature.



Why explaining ‘aboutness’ is difficultWhy explaining ‘aboutness’ is difficult

thoughts about things that exist There's no such thing as 'Intentional string'.

The asymmetry problem: Aboutness can't be resemblance

Bush is a jerk

aboutness



An attempt to explain what ‘aboutness’ isAn attempt to explain what ‘aboutness’ is

My thought is about Bush = my thought was ‘caused in the right sort of way’ by Bush.

Bush is a jerk

aboutness

Causal chain



Why the causal account doesn’t workWhy the causal account doesn’t work

We can also think about things that don’t exist.

It would be fun to

ride a unicorn.

Causal chain??



Cartesian DualismCartesian Dualism

Minds and Matter are two fundamentally different kinds of “substances”

ThoughtsFeelings


Physical stuff (matter)

Mental stuff (minds)

Consciousness

Intentionality

Thought



Problems with Cartesian Dualism (I)Problems with Cartesian Dualism (I)

It's mysterious what the "mind substance" is. What it’s not:

Not made of matterNot located in spaceNot ‘extended’ ...



Problems with Cartesian Dualism (II)Problems with Cartesian Dualism (II)

It’s a mystery how minds can interact causally with things made of matter. Mental causing physical:

I’m going to raise my arm.

Causes

Mental substance (mind) Matter



Problems with Cartesian Dualism (II)Problems with Cartesian Dualism (II)

Physical causing mental:

Sound experienc

e

sound waves

Causes



Problems with Cartesian Dualism (III)Problems with Cartesian Dualism (III)

Are dualism and gradual evolution consistent?

??



Problems with Cartesian Dualism (IV)Problems with Cartesian Dualism (IV)

It makes the Other Minds problem very hard to solve.

Vs.

ThoughtsFeelings




“Materialist” solutions to the Mind – Body Problem

“Materialist” solutions to the Mind – Body Problem

Materialism: The claim that everything in the universe is made up of matter.



The advance of materialismThe advance of materialism

The advance of science has made materialism look very plausible to many philosophers & scientists. Astronomy: The heavenly bodies are made of matter and obey the laws of physics.

earth

“heavens”




Evolutionary biology: No non-material processes or forces (e.g. God) are needed to explain the design in the biological world.

Spooky stuff?

Spooky stuff?




Advances in physiology & understanding the genetic code: There is no need for a “life force” ("elan vital").

“life force”

“life force”

Live tiger

Dead tiger




Advances in understanding the way the brain works – helped by imaging technology – makes it increasingly plausible to believe that mental phenomena like thought and consciousness might be explained in terms of brain processes

Spooky stuff??

Spooky stuff??



The “Reductive Materialism” hypothesisThe “Reductive Materialism” hypothesis

The “Reductive Materialism” hypothesis: social sciences can be reduced to (i.e. explained by appeal to)

psychology psychology can be reduced to biology biology can be reduced to chemistry chemistry can be reduced to physics



Behaviorism Behaviorism

The way we tell that (e.g.) you're in pain is by observing your behavior. The inspiration for behaviorism: maybe what it means to say you're in pain also involves your behavior.



‘Behaviorism’ in psychology‘Behaviorism’ in psychology

Methodological (or: psychological) behaviorists included B. F. Skinner Methodological behaviorism: If there is anything more to mental states than dispositions

to behave in certain ways, that 'extra bit' has nothing to do with science.

I am feeling angry



‘Behaviorism’ in philosophy‘Behaviorism’ in philosophy

Analytical (or: philosophical) behaviorists included Ludwig Wittgenstein and Gilbert Ryle: there is nothing more.

I am feeling angry

EQUALS



Analytical behaviorismAnalytical behaviorism

Analytical behaviorism: Claims about mental states and processes can be “translated” into claims about patterns of behavior.

Example:

“Tom has a toothache” = “Tom moans; Tom says his tooth hurts; if someone touches Tom’s tooth, Tom screams; etc."



Analytical behaviorismAnalytical behaviorism

“Jenny is hungry” = ?? “Jason wishes he could quit school” = ??



Behaviorism and the Problem of Other MindsBehaviorism and the Problem of Other Minds

I am feeling angry

EQUALS



Problems for behaviorism (I): Undefinable mental states

Problems for behaviorism (I): Undefinable mental states

Some mental states don't seem to be definable in this way. Listening to Bob Dylan Thinking about how big the universe is



Problems for behaviorism (II): Circular definitions


Behaviorist “definitions” of mental state terms all turned out to be circular (or just plain wrong).

‘Tom believes it will rain today’ = ‘Tom will either stay at home or drive to school today’

IF Tom wants to stay dry, and Tom doesn’t believe there’s a shelter at the bus stop, and...





“James believes the exam will be hard”= ....??



Problems for behaviorism (III):The 'inverted spectrum' problemProblems for behaviorism (III):

The 'inverted spectrum' problem

It seems possible for one person to have their spectrum of color experiences 'inverted' relative to another's. But according to behaviorism, this is not possible.

The flower looks yellow

The flower looks yellow



Problems for behaviorism (IV): Some wrong predictions


For behaviorists, two people who behaved in just the same way would have the same mental states. But there are cases in which this is clearly crazy. Dennett’s thought experiment: curare plus “amnestic”

“How did it feel?”

Administer general

anaesthetic

operation





“Curare”: paralyses all voluntary muscles “Amnestic”: Has no effect until 2 hours after ingestion, whereupon it wipes out

memory of those two hours

“How did it feel?”

Administer curare + amnestic

operation



... The problem (an argument against behaviorism):

... The problem (an argument against behaviorism):

(P1) Behaviorism predicts that the patient who is given general anaesthetic has the same experiences as the patient who is given curare + amnestic.

(P2) But that’s wrong! One is unconscious, and the other is in excruciating pain.

Therefore,

(C) Behaviorism is false.



The (Type-Type) Identity TheoryThe (Type-Type) Identity Theory

The type – token distinctionthe the

Greaves's belief that snow is white & your belief that snow is white.

Snow is white

Snow is white



The (Type-Type) Identity TheoryThe (Type-Type) Identity Theory

The type-type identity theory: Mental state types are identical with brain state types

Examples of mental state types: the belief that snow is white a burning pain in the index finger the thought that 17 is a prime number

Example of a type-type identification: "Pain is c-fibers firing"

pain

Same event (type)



How the theory deals with the Other Minds Problem

How the theory deals with the Other Minds Problem

..??



Problem for the (Type) Identity Theory: “Chauvinism” about the mental

Problem for the (Type) Identity Theory: “Chauvinism” about the mental

According to type-type identity theory: Animals with brains significantly different from

ours can’t feel pain or have other mental states If there are organisms in the universe whose

chemical composition is different from ours, they can’t feel pain or pleasure, and they can’t think.

Extra-terrestrials can’t even think about math. pain

7x5=35



Functionalism (aka “machine functionalism”)

Functionalism (aka “machine functionalism”)

The emergence of computers and the computer model of the mind. Computers are symbol manipulators Programs specify how the symbols are to be manipulated.

ADDING PROGRAM

2

35



Programs and physical devicesPrograms and physical devices

Many different sorts of physical devices can run the same program...



Minds and programsMinds and programs

Minds are to brains as programs are to computers “The mind is the brain’s program”

Inputs (mouse clicks, keyboard

strokes)

Outputs (screen displays; printouts)

Inputs (light rays; hammers hitting

thumb)

Outputs (body movements; screams;

sentences spoken)

PROGRAM

PROGRAM



‘Functional states’‘Functional states’

Mental state concepts are functional concepts; mental states are functional states (not physical states)

‘Functional states’ for the adding program:

Input 2 Input 3

Output 5

Computer state: ‘remember that a 2 has been input, and get ready to

add a 2nd number’

Computer state: ‘ready to do an add calculation’

Functional states



‘Functional states’ cont’d‘Functional states’ cont’d

Desire to stay dry

Belief that there is no

shelter at the bus stop

Input: See that it’s raining

Belief that it’s raining

Output: Look for car keys

Functional states



What is...What is...

The functionalist solution to the Other Minds Problem?

The functionalist solution to the chauvinism problem?

pain

pain

?

?



Strong AIStrong AI

A radical (?) implication of functionalism: “Strong AI” -- It is possible to build artificial minds with real mental states. A computer running the same program that your brain

is running would have the same mental states that you have.

It would be conscious, and thus feel pains and pleasures, have emotions, etc.

It would have thoughts with real intentionality.



Can machines think?Can machines think?

If they can, then the fact that functionalism predicts that they can counts in favor of the functionalist theory. If not, it counts as an objection to functionalism.

The Turing test – if a machine passes the Turing test, we cannot tell that it isn't really thinking It is a further step to say that if a machine passes the

Turing test, then it is thinking. But perhaps (?) this extra step is very plausible.

“What do you think about Saddam’s

trial?”

“I don’t normally approve of the death penalty, but this guy deserves everything he gets.”



Searle’s Critique of Functionalism and Strong AI

Searle’s Critique of Functionalism and Strong AI

Roger Schank’s project: Getting a computer to understand stories and answer questions about them the way people do.

A man went into a restaurant and ordered a hamburger. When the hamburger arrived it was burnt to a crisp, and the man stormed out of the restaurant angrily, without paying for the burger or leaving a tip.

Did the man eat the hamburger?

No



What Schank’s computer is doingWhat Schank’s computer is doing

It’s manipulating symbols. Does this mean that it understands what the symbols mean (i.e.

understands the story, and understands its replies to the questions)?

Thinking of a restaurant

sceneaboutness



Searle’s argumentSearle’s argument

Understanding is an ‘intentional state’ – when you understand a story, you understand what it is about.

Searle’s going to argue that the computer could be manipulating symbols in all the right ways, without understanding the story (= without having ‘intentionality’).

The "Chinese room argument": An argument that passing the Turing test is not sufficient or thinking.



The setup of the "Chinese room”The setup of the "Chinese room”

Input: Output:



Searle’s argumentSearle’s argument

(P1) Neither Searle nor any other part of the Chinese Room really understands Chinese.Therefore,(C1) The Chinese Room [i.e. the system] does not understand Chinese. (From (P1))(P2) But the Chinese Room perfectly simulates someone who does understand Chinese.Therefore,(C2) Simulating understanding is not sufficient for having understanding. (From (P2), (C1))Therefore,(C3) Even if Schank's computer perfectly simulates human understanding of stories, it does not

follow that Schank's computer really understands stories.



Searle’s Account of IntentionalitySearle’s Account of Intentionality

It is a “causal product” of the right kind of biological system.

ADDING PROGRAM

2

35

adding

Not a “causal product” of the

symbol manipulation




Pick up brick and throw at window

Window

breaks

Causal product of brick being

thrown




Searle’s Account of Intentionality It cannot be created simply by

symbol manipulation.

Searle makes the same claims for consciousness. intentionalit

y

intentionality

intentionality

intentionality

???



A Problem for Searle’s ViewA Problem for Searle’s View

Either intentionality and consciousness are restricted to brains like ours in which case he is committed to chauvinism

Or brains quite different from ours can also produce intentionality & consciousness in which case the Other Minds Problem looks to be unsolvable since

we can’t tell which brains just simulate consciousness & intentionality & which really have it.



Some questions for YOU to ponderSome questions for YOU to ponder

Can a suitably sophisticated computer which is NOT made out of “meat” like the human brain have real intentionality (and thus real thoughts)? have real consciousness (feel real pain & pleasure, and know what it

is like to experience colors & tastes)?

Does it matter? If so, why?



Some questions for YOU to ponderSome questions for YOU to ponder

Can an extra-terrestrial with a suitably sophisticated brain that is very different from our brain have real intentionality (and thus real thoughts)? have real consciousness (feel real pain & pleasure, and know what it is like to

experience colors & tastes)?

How can we KNOW whether the computer or the extra-terrestrial has REAL consciousness and REAL intentionality?

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